This invention relates generally to improvements in scrolling backlighting systems of the type used in Liquid Crystal Display Television (LCD-TV) applications for motion artifact reduction and, more particularly, to the invention resides in apparatus for scrolling high intensity light from a source over a backlight panel for an LCD-TV display in a manner which overcomes problems normally associated with scrolling backlight systems.
In the transmitting mode of operation of an LCD, light emanating from an appropriate light source is directed to a panel located on the opposite side of the LCD display from the viewer.
In order to reduce motion artifacts in LCD-TV displays, it has been found useful to provide the light in such a manner that a beam is continually scrolled over the panel. Presently, scrolling backlight systems used in the reduction of motion artifacts for LCD-TV use either direct backlit cold cathode fluorescent lamps (CCFLs) or edge-backlit white RGB (red, green, blue) LEDs, the latter of which requires substantially more power than the former. Both systems commonly experience undesirable characteristics such as non-uniformity of illumination over the area of the panel and/or brightness level.
The present invention is directed to overcoming one or more of the problems or disadvantages associated with the relevant technology.
Light from an appropriate source is directed into the open end of a cylindrical drum, the other end of which is closed. The drum has a highly reflective inside surface and an orifice of predetermined dimensions in the cylindrical wall. The drum is rotated at constant angular velocity about its axis, causing the beam of light passing through the orifice to likewise rotate in a circular pattern. An array of optical fibers is arranged with a proximal end of each fiber positioned on a circle coaxial with the axis of the drum and spaced outwardly from the position on the drum""s outer surface which includes the orifice. The distal ends of the fibers are positioned linearly along an edge of the backlighting panel of an LCD array with the distal ends in the same sequence as the proximal ends. Thus, the beam passes through the orifice and sequentially impinges upon the proximal ends of the fibers, and is thereby directed to and scrolled continuously across the panel to provide backlighting with a sufficient and uniform level of brightness.